JPS6311915Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a control device for a DC motor that smoothly winds and unwinds a rope stretched between two DC motors without loosening.

Conventionally, when operating a swing winch or an ingot buggy truck in a dredge, the above-mentioned loads are transported using ropes stretched between two DC motors. Both cannot be operated at constant speed and constant torque, and the rope becomes slack during operation or when stopped. For this reason, there is a drawback that the momentary tensioning of the rope at the start of operation causes fatigue and other problems in operation. On the other hand, in order to eliminate this drawback, it is necessary to add a circuit for applying static tension to the control circuit of the DC motor, which has the disadvantage of making the control circuit complicated and costly.

The present invention is intended to improve such conventional problems, and when the rope is at rest, a static tension is applied to it, and when the rope is running, the DC motor on the rewinding side is driven by voltage while the DC motor on the unwinding side is driven. An object of the present invention is to provide a control device for a DC motor that allows a rope stretched between two DC motors to run smoothly in both forward and reverse directions by applying a constant braking current. Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows the configuration of a mechanical system that controls running loads in forward and reverse directions using two DC motors, and the thyristor Leonard method, Ward Leonard method, and other control methods are optionally adopted as the speed control method. can. Here, a control system employing the Ward Leonard method will be explained. Reference numerals 1 and 2 denote a DC generator and a DC motor that are connected in series with each other. The DC generator 1 is driven by a prime mover such as another drive motor or an engine, and the generated voltage drives the DC motor 2. Reference numerals 3 and 4 denote separately excited type excitation windings. In particular, by adjusting the current flowing through the excitation winding 3, the voltage applied to the armature of the DC motor 2 can be freely and finely adjusted. These constitute a drive system on the rewinding side. on the other hand,
Reference numerals 5 and 6 are a DC generator and a DC motor similar to those described above, and these are provided with excitation windings 7 and 8, and these constitute a drive system on the winding side. Drums 11 and 12 that are driven in opposite directions are attached to the drive shafts 9 and 10 of the DC motors 2 and 6, and a rope 13 with one end fixed to each drum is wound around these drums.
This is fed out from one of the drums 11, 12 to the other and rolled in. A running load 14 is fixed to the tensioned portion of the rope 13. Note that the running directions of the rope 13 are referred to as a winding direction A and a winding direction B for convenience. When winding and unwinding the rope 13 using the two DC motors 2 and 6, stationary tension is applied to the rope 13 so that it does not loosen while the rope is stopped, and a driving command in a certain direction is applied. When the current is given, the DC motor 6 on the winding side is voltage controlled and operated at a predetermined speed so as to move the traveling load in that direction, and the braking current is applied to the DC motor 2 on the other winding side. The purpose is to obtain dynamic tension by constantly applying a constant brake while being pulled by the DC motor 6 on the winding and winding side. Also,
When decelerating and stopping, a brake current is applied to the DC motor 6 on the winding side to decelerate it, and at the same time, a brake current above a certain level is applied to the DC motor 2 on the rewinding side to reduce the speed of the winding side. This is to help decelerate the DC motor 2 and to perform an operation in which static tension is applied to both DC motors 2 and 6 again when the motor is stopped. That is, during rewinding operation, a command is issued to supply a constant braking current to the DC motor 2, while when switching to winding operation, a command is given to supply the drive current necessary for operation. Make it. In other words, both DC motors 2 and 6 are under automatic voltage control during drive operation (when winding up the rope 13), and automatic current control when used for unwinding the rope 13 on the sending side. All you have to do is to do each of them. Further, switching between voltage control and current control of each DC motor 2, 6 is determined by the voltage setting input of each DC motor 2, 3, and is performed by an automatic voltage control device.

FIG. 2 is a circuit diagram of a control system that realizes such an operation, which causes the voltage and current shown in FIG. supply. In FIG. 2, reference numeral 15 denotes a control circuit voltage setter made of a variable resistor, which provides control voltages of +15V and -15V when fully rotated in the left and right directions, respectively. Two control circuits, one on the winding side and one on the rewinding side, are connected to the voltage setting device 15. First, 16 is an automatic voltage adjustment amplifier for controlling the DC motor 6, and the above-mentioned set voltage and a voltage detection signal for drive control are input to the input side of the amplifier. These comparison output signals are input to the automatic current adjustment amplifier 17 together with a current detection signal for drive control. Furthermore, the comparison output signal is supplied to a field control amplifier (not shown),
It acts on the field winding 7 to obtain the field current shown in FIG. 3d. On the other hand, 18 is a signal polarity inversion amplifier on the rewinding side, and its output signal and DC motor 2
The voltage detection signal for drive control is input to the automatic voltage adjustment amplifier 19, and the comparison output signal and the current detection signal for drive control are input to the automatic current adjustment amplifier 20.
is input. The comparison output signal is supplied to a field control amplifier (not shown), and the third
It acts to obtain the field current shown in Figure g. Here, when the rope 13 is run by the drive of the DC motors 2 and 6 and the load 14 is moved to the right (in the direction of arrow A), the voltage setting device 15 is rotated clockwise to automatically adjust the set voltage. Add to amplifier 16.
Here this set voltage is compared with the voltage detection signal,
Get an auto-adjusted voltage output signal. Further, this signal is compared with a current detection signal in the automatic current adjustment amplifier 17, and the field current control amplifier is controlled by the comparison output signal. That is, the DC motor 6
are the voltage and current output signals in FIG. 3b,
The drive is controlled by the voltage and current shown in c. On the other hand, the above-mentioned set voltage is also input to another automatic voltage adjustment amplifier 19 via the polarity inversion amplifier 18, and an automatically adjusted voltage output signal is obtained in the same manner as described above, which is added to the automatic current adjustment amplifier 20. The control amplifier of the excitation winding 3 is controlled via the field current control signal. When the load 14 is caused to run at the speed shown in FIG. 3a, the DC motors 2 and 6 are controlled by the field control amplifier as described above.
The field current of is set as shown in Fig. 3d and e. As a result, the driving voltage of each DC motor 2, 6 is t ₁ ~
The voltage gradually rises within t ₂ and becomes constant voltage operation at t ₂ as shown in Fig. 3 b and e. That is, they rotate at a constant speed. At this time, the driving current flowing through each DC motor becomes a substantially equal large current that rises in a pulse manner to obtain a large starting torque, as shown in FIG. 3c and f. Note that the drive current shown in FIG. 3c is a braking current in the opposite direction that applies static tension to the rope 13 before _t1 . Then, the DC motors 2 and 6 rotate at a constant speed, and the rope 13
During the period from t ₂ to _{t 3} when the vehicle is traveling at a constant speed, the drive voltage is constant and the drive current also shows a steady value. However, the drive current flowing through the DC motor 2 on the rewinding side drops significantly after the rise described above, and changes to a braking current that absorbs the drive force in the right direction. This constant braking current is supplied only to the electric motor 2. The field current to obtain such voltage-current characteristics is shown in Figure 3d,
Shown in g. The rope 13 therefore carries the load 14 under constant tension during this constant speed operation period. On the other hand, when the load 14 reaches a predetermined position and is to be stopped, the voltage setting device 15 is rotated counterclockwise to set the voltage setting value to, for example, O volts. At this time, the field current gradually falls within t ₃ to _{t 4} by the control circuit described above, and the rotational speed and drive voltage of both DC motors 2 and 6 similarly fall, and finally they stop and reach OV. Become. However, a braking current is applied to the DC motor 6 to urge it in the previous direction of rotation, while an excitation current is applied to the DC motor 2 to drive it in the opposite direction. This excitation current is maintained constant between t ₄ and _{t 5} , and the rope 13 remains balanced and tensioned by both of these excitation currents. Next, the rope 13 is moved to the left (in Fig. 1) so as to transport the load 14 in the opposite direction.
When moving in the direction of arrow B), voltage setting device 1
5 to the left, and the excitation current shown at t ₅ to _{t 6} in FIG. 3 d and g is obtained by the control circuit. This excitation current is applied in the negative direction to drive both DC motors 2 and 6 in the opposite direction to the above. Therefore, the rotational speeds and drive voltages of both electric motors 2 and 6 gradually decrease significantly, and the drive current also decreases as shown in FIGS. 3c and 3f. However, during time t ₆ to _{t 7} when the rotational speed and drive voltage are constant, the drive current rises back up and maintains a constant value, but the excitation current of the DC motor 6 remains at a constant value opposite to the rotation of the DC motor 2. It becomes a brake current,
The rope 13 between the two DC motors 2 and 6 is tensioned to run in the unwinding direction. In this case, the excitation current of the DC motor 2 is sufficiently larger than the excitation current of the DC motor 6. When the load 14 reaches a predetermined position and the rope 13 stops running in the direction of arrow B, each exciting current rises between _t7 and _t8 , but the rising speed of the exciting current in the exciting winding 7 is somewhat faster. , the rotational speed and driving voltage of both DC motors 2 and 6 are Ov
At the point in time, the current rises in the direction of driving the DC motor 6 in the winding direction, and the excitation current of the DC motor 2 is maintained at a value that still urges the DC motor in the unwinding direction. At this time, the drive current is a pulsed current with a large rise so as to rapidly stop both the DC motors 2 and 6.
However, after _t8 , a braking current in the rewinding direction flows through the DC motor 2, keeping the tension of the rope 13 constant.

Note that when the automatic voltage adjustment amplifier 19 shown in FIG. 2 is supplied with a set voltage of opposite polarity (for example, positive polarity) to the automatic voltage adjustment amplifier 16 of the winding side control circuit, its output polarity is set to an appropriate negative polarity. A constant setting signal is given to the automatic current adjustment amplifier 20 in the next _stage , and the current of the DC motor 2 on the rewinding side is controlled so that the brake current as described above is obtained. It is designed to have such output characteristics. The output characteristic diagram of the automatic voltage adjustment amplifier 19 at this time is shown in FIG. 5A, which will be described later. On the contrary, rope 1
3 is rewinded by the DC motor 2, the operation of the control circuit is completely reversed, so that the _brake current _and
The brake currents from t ₂ to _{t 3} are equal in magnitude and different in direction. Furthermore, even when the set voltage is O when stopped, the outputs of the automatic voltage adjustment amplifiers 16 and 19 are constant negative values as shown in FIG. 5A, so that a static tension equivalent to the output voltage V _L can be obtained.

In order to carry out the control according to the present invention, the details of the automatic voltage adjustment amplifiers 16 and 19 are respectively configured as shown in FIG. In other words, these amplifiers include an input resistor Rin that receives the difference between the set voltage + and the detected voltage value - shown in Figure 2, amplifier A, capacitor Cf, resistor Rf, diodes D ₁ , D ₂ , limiter adjustment setting device V _R1 ,
It consists of V _R2 and variable resistor V _R3 . When the contact RY is in the current position "off", the input/output characteristics shown in Figure 5A are obtained, the DC motor on one side is driven by automatic voltage adjustment, the DC motor on the other side is in brake operation by automatic current adjustment, and the other side is in brake operation with automatic current adjustment. If the contact RY is set to the "ON" position, both DC motors will operate with automatic voltage adjustment, and the input/output characteristics will be as shown in Figure 5B.

As described above, according to the present invention, the driving voltage and current of the two DC motors can be adjusted simply by switching the speed setting signal applied to the control circuit, and this allows the rope to be reciprocated while the rope is running and when it is stopped. Sometimes the desired tension can be maintained. Therefore, it is possible to prevent mechanical damage and fatigue caused by slack in the rope during startup, and to prevent other problems caused to the DC motor. Furthermore, the control means for realizing such an effect can be easily configured by, for example, an integrated circuit, and two DC motors can be easily controlled manually or automatically by continuous operation of one signal setting device. Can be controlled. Therefore, there is no need for a control circuit or a multi-contact type changeover switch to obtain static tension, the structure can be made smaller and simpler, and accidents such as contact failures can be prevented.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an outline of the control device for a DC motor according to the present invention, Fig. 2 is a control circuit diagram thereof, and Figs. 3 a to g show the speed, driving voltage and current of the DC motor, and the DC generator. FIG. 4 is a detailed diagram of the automatic voltage adjustment amplifier, and FIGS. 5A and 5B are its output characteristic diagrams. 2, 6...DC motor, 13...rope, 14
...Load, 15...Drive signal setting device, 16, 19
...Automatic voltage adjustment amplifier, 17,20...Automatic current adjustment amplifier.

Claims (1)

[Claims for Utility Model Registration] A DC motor that drives and controls a DC motor of a device that alternately winds a rope stretched between two DC motors and causes a load attached to the rope to travel in forward and reverse directions. In the control device, a drive signal setting device for drive control of the two DC motors; an output signal of the drive signal setting device and a voltage detection signal of one of the two DC motors are input; a first automatic voltage adjustment amplifier whose output changes according to the input and which emits a constant output when the input is below a predetermined value; a signal obtained by inverting the output of the drive signal setting device; and the other of the two DC motors. a second automatic voltage adjustment amplifier that receives a voltage detection signal of the first automatic voltage adjustment amplifier, changes its output according to the input, and emits a constant output when the input is less than a predetermined value; and the output of the first automatic voltage adjustment amplifier. a first automatic current adjustment amplifier that amplifies the deviation between the current detection signal of the one DC motor; and a first automatic current adjustment amplifier that amplifies the deviation between the output of the second automatic voltage adjustment amplifier and the current detection signal of the other DC motor. a second automatic current adjustment amplifier, the one DC motor is controlled based on the output of the first automatic current adjustment amplifier, and the other DC motor is controlled based on the output of the second automatic current adjustment amplifier. A control device for a DC motor, characterized in that the electric motor is controlled, and at least when one DC motor is driven at a constant voltage and when the other DC motor is stopped, a braking current is applied to the other DC motor to drive the other DC motor in the opposite direction.